Fix store skipped checks results

[patrick-levesque]

This PR fixes an issue with storing results using EloquentHealthResultStore for skipped checks when a frequency method such as ->everyFiveMinutes() is used. The ended_at field is required and was not set for skipped checks. Also added ResultStores tests for skipped checks.

[freekmurze]

Thanks! Could you take a look at the failing tests?

[patrick-levesque]

"But it works on my computer." 😂 All tests pass locally and I didn't modify this failing test. After checking, I think it is possible that DatabaseConnectionCountCheckTest only gets 1 connection which fails the expect($result->getNotificationMessage()) contains connections (plural). I will update this test to expect only connection and it should avoid this issue.

[patrick-levesque]

I had to merge recent commits with Capitalize short summary for PingCheck to get all tests pass. 😅

[freekmurze]

Thanks!